irqchip: armada: Fix chained per-cpu interrupts

On the Cortex-A9-based Armada SoCs, the MPIC is not the primary interrupt controller. Yet, it still has to handle some per-cpu interrupt.

To do so, it is chained with the GIC using a per-cpu interrupt. However, the current code only call irq_set_chained_handler, which is called and enable that interrupt only on the boot CPU, which means that the parent per-CPU interrupt is never unmasked on the secondary CPUs, preventing the per-CPU interrupt to actually work as expected.

This was not seen until now since the only MPIC PPI users were the Marvell timers that were not working, but not used either since the system use the ARM TWD by default, and the ethernet controllers, that are faking there interrupts as SPI, and don't really expect to have interrupts on the secondary cores anyway.

Add a CPU notifier that will enable the PPI on the secondary cores when they are brought up.

Cc <[email protected]> # 3.15+

Signed-off-by Maxime Ripard <[email protected]>

---
Changes from v1:
- Renamed the function and notifier names

 drivers/irqchip/irq-armada-370-xp.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

drivers/irqchip/irq-armada-370-xp.c +20 -1

index 463c235acbdc..4387dae14e45 100644
@@ -69,6 +69,7 @@ static void __iomem *per_cpu_int_base;
 static void __iomem *main_int_base;
 static struct irq_domain *armada_370_xp_mpic_domain;
 static u32 doorbell_mask_reg;
+static int parent_irq;
 #ifdef CONFIG_PCI_MSI
 static struct irq_domain *armada_370_xp_msi_domain;
 static DECLARE_BITMAP(msi_used, PCI_MSI_DOORBELL_NR);

@@ -356,6 +357,7 @@ static int armada_xp_mpic_secondary_init(struct notifier_block *nfb,
 {
 	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
 		armada_xp_mpic_smp_cpu_init();
+
 	return NOTIFY_OK;
 }
 

@@ -364,6 +366,20 @@ static struct notifier_block armada_370_xp_mpic_cpu_notifier = {
 	.priority = 100,
 };
 
+static int mpic_cascaded_secondary_init(struct notifier_block *nfb,
+					unsigned long action, void *hcpu)
+{
+	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
+		enable_percpu_irq(parent_irq, IRQ_TYPE_NONE);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block mpic_cascaded_cpu_notifier = {
+	.notifier_call = mpic_cascaded_secondary_init,
+	.priority = 100,
+};
+
 #endif /* CONFIG_SMP */
 
 static struct irq_domain_ops armada_370_xp_mpic_irq_ops = {

@@ -539,7 +555,7 @@ static int __init armada_370_xp_mpic_of_init(struct device_node *node,
 					     struct device_node *parent)
 {
 	struct resource main_int_res, per_cpu_int_res;
-	int parent_irq, nr_irqs, i;
+	int nr_irqs, i;
 	u32 control;
 
 	BUG_ON(of_address_to_resource(node, 0, &main_int_res));

@@ -587,6 +603,9 @@ static int __init armada_370_xp_mpic_of_init(struct device_node *node,
 		register_cpu_notifier(&armada_370_xp_mpic_cpu_notifier);
 #endif
 	} else {
+#ifdef CONFIG_SMP
+		register_cpu_notifier(&mpic_cascaded_cpu_notifier);
+#endif
 		irq_set_chained_handler(parent_irq,
 					armada_370_xp_mpic_handle_cascade_irq);
 	}

On the Cortex-A9-based Armada SoCs, the MPIC is not the primary interrupt controller. Yet, it still has to handle some per-cpu interrupt.

To do so, it is chained with the GIC using a per-cpu interrupt. However, the current code only call irq_set_chained_handler, which is called and enable that interrupt only on the boot CPU, which means that the parent per-CPU interrupt is never unmasked on the secondary CPUs, preventing the per-CPU interrupt to actually work as expected.

This was not seen until now since the only MPIC PPI users were the Marvell timers that were not working, but not used either since the system use the ARM TWD by default, and the ethernet controllers, that are faking there interrupts as SPI, and don't really expect to have interrupts on the secondary cores anyway.

Add a CPU notifier that will enable the PPI on the secondary cores when they are brought up.

Cc <[email protected]> # 3.15+

Signed-off-by Maxime Ripard <[email protected]>

---
Changes from v1:
- Renamed the function and notifier names

 drivers/irqchip/irq-armada-370-xp.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)